Boiler



Patented Aug. 25, 1931 UNITED STATES ASHUR U. WETHEBIBEE, OF CHICAGO, ILLINOIS BOILER Application led February 25, 1925. Serial No. 11,389.

v My invention has reference to water-tube boilers of the Stirling type', that is, a ring circuit boiler in which four main drums forming a quadruple series of drums, are arranged in series communication through interposed banks of tubes with a lower bank over the fire box so that the gases of the gas-current first pass substantially crosswise thereof, the two lower drums being placed with the one in front only slightly above the one or mud drum in rear thereof. or at a relatively low level, so that the lower bank oftubes run at a slight inclination sufficient to cause circulation and are substantially at right angles to the flow of the gases from the furnace grate or other heating source, and of such a length as to insure that they will be entirely, or fully and completely exposed to the hot gases.

The invention also embodies a novel arrangement of drums in quadrangular relation and including upper steam and water drums, a lower front water drum and a still lower rearward mud drum related to each other in a novelmanner andinterconnected by a novel arrangement of tuhesor banks of tubes with a novel arrangement of baffles or baffle Walls and a superheater of novel p arrangement whereby maximum steam generating efliciency with a minimum of fuel consumpti'ontogether with the production .of drier steam, greater steaming capacity y and economical manufacture `is provided for,

although it is to be understood'that a great latitude is allowed in the exact arrangement of the parts including the superheater and balies referred to.

By way of explanation, it is pointed out that existing water tube boilers are com# monly divided into two general classes, bent and straight tube boilers. Each class has its advantages, and the object of 'this invention is to combine the important advantages of both types, While eliminating as far as 35 possible the important disadvantages ofv both.

l This invention is a boiler of the bent tube' class, thus securing the advantages of low first cost, and low cost of repairs and maintenance, and4 inherent ease of inspection,

while eliminating the high first cost and high cost of maintenance of the straight tube class of boilers, for hand holes, gaskets, etc. In the present state of the art of furnace design and construction, the length of m those'tubes exposed to radiant heat would be so proportioned as to maintain the furnace temperature within such limits as would not be destructive to the furnace linings.

With the above and other objects. in view, I have illustrated in the accompanying drawing, forming a part of this specification, a practical and preferred embodiment of the invention illustrating its operating principles and constructional features, in which thefigure is a vertical sectional view, partly in elevation, of a water tube steam generator or boiler constituting my invention, the setting or Wall structure thereof being in section.

i By reference to the drawing, it will be ,noted that the setting or wall structure 10 includes the front Wall 11 and the rear walll 12. A suitable heating means 'or source is provided and shown partly beneath the horizontal wall 13 at the front portion of the lurnace setting such as a coal burning fire box and grate or other suitable fuel burner, either coal or oil or gas, but which, in the present instance, is shown as an endless grate member 14 trained over afroller 15 and provided for gradual rearward feeding and burning of the fuel thereon, and from which the generated heated gases and products ofcombustion pass upwardly through the setting.

A lower or mud drum 16 is arranged across the furnace near the rear wall thereof, but slightly spaced therefrom, and above the fire wall 17 of the furnace or boiler setting as clearly\seen inthe drawing.

A water drum 18 is arranged to project partly into the front wall 11 but 'not in contact therewith, being separated by a packing 19 in a circular recess cut in said wall to allow movement of said drum due to expansion which recess or cavity receives the waterreceiving drum 18 which is disposed slightly above the lower or mud drum 16, Adjacent the reinforced top wall or cover 2O of the boiler structure or furnace setting are front and rear steam and water drums 21 and 22, said drums being placed substantially at the same level, that is, having a common center on a horizontal plane but the former being preferably lslightly larger than the latter and constituting the principal steam and water receiving drum. These drums, 21 and 22, are spaced apart horizontally, the drum 21 being spaced from the front wall 11 and disposed completely rearwardly of the water drum 18 and forwardly of the lower or mud drum 16 but in a Vertical plane closer to the drum 18 than to the dru1n16, whereas the drum 22 is disposed substantially directly above the drum 16, that is, with their centers substantially in the same vertical plane.

A lower set or bankl of tubes 23 extends between the lower front portion of the mud drum 16 and the lower rear portion of the v water drum 18, these tubes being arranged at a slightupward inclination forwardly, shown in the drawing as about 12 to 15 degrees but comparatively or substantially horizontal. This inclination may be varied. That is, these tubes are arranged at a slight inclination from the horizontal to be exposed to the radiant heat of the fire and so that the hot gases from the furnace fire box pass the same substantially at right angles,

vthat is, normal or perpendicular to their axes, this crosswise flow of the gas current for the first pass of g-ases securing the advantage of better heat transfer due to the direct impingement ofthe hot particles of the gases and products of combustion on the tubes, the scouring off ofVthe gas film which tends Vto cling to the tubes, and the mixing ,of these gases during their flow between and around the tubes. This is analogous to the passage of the gases through the first pass ofY the common v'type of nearly horizontal straight tube boilers, and eliminates the tendency for the gases to lane through the center of the gas passages when the gas passes parallel to the tubes in many water tube boilers. It is further to be'noticed and pointed out that the lower bank of tubes 23 subjected to radiant heat, is unobstructed by bailes) or baille walls so that the full lengths thereof are exposed to the radiant heat and heated gases or products of combustion from the fire, as well as the lower drums at the portions to which the tube ends are connected, the `'gases taking a tortuous passage between and around the tubes when hottest, in addition to exposing the -tubes to the radi- Y ant heat of the fire.

In addition to the radiant heat bank or upiiow water tubes 23, connecting the drums 16 and 18, the water drum 18 is connected to theupper steam and water drum 21 by means of an upper upflow bank of water and steam tubes 24 which extends from thevupper portion of the water drum 18 to the lower portion of the steam and water drum 21 and are inclined upwardly'and rearwardly slightly, being disposed substantially vertically as shown and subjected to the action of the hot gases after passing from the lower bank of water tubes 23 in conjunction with suitable baffle walls which may be employed to cause the gases to traverse or be forced to pass partly or wholly crosswise of said upper .bank 24 as will be hereinafter more particularly described.

A downflow bank of water tubes 25 extends between the lower rear portion of the drum 21 and the upper forward portion of the drum. 16, and one of these tubes or a series thereof, that is, the lower row or rows, may be bent in angular relation as indicated at 26 or to extend substantially downwardly in a vertical direction at their upper portions from the drum 21 and then in an ir lined direction rearwardly to the drum 16 spaced from the tubes 25 and in triangular spaced relation with respect thereto. It is also to be noted that the arrangement of the drums 16, 18 and 21.in triangular relation', as distinct from the quadrangular relation of the drums 16, 18, 21 and 22, also provides for the triangular arrangement of the banks of tubes 23, 24 and 25, which banks .form the ysides of the triangle connecting the `corners formed bythe drums 16, 18 and 21,

thus'providing an intervening or interme- ',diate space v27 between the tubes 23, 24 and 26 or 25 if the tubes 26 bent as described are omitted, and also a space 28 between the tubes 25 and 26 in case the latter ,angular tubes are employed as described.

A further set or bank of tubes is designated at 29 and extends between the upper rear portion ofthe mud drum 16 and the bottom or lowest portion of the steam and water drum 22. These tubes are preferably slightly inclined forwardly but of less inclination than the tubes of the bank 25 of the down'- flow set, andinay be vertical if desired, and constitute a further set or series. of downflow tubes for water, but from which the steam which is liberated therefrom rises or flows upwardly at and into the steam and water drum'22.4 This latter drum'terminates in spaced relation tothe rear or back wall 12 of the setting to provide an outlet port or breeching 30 to the smokestack at the rear of the setting and with which cooperates a-v control -valve or dampery 31. waterl iowsI down tubes 29.

The upper drums, 21 and 22, are connected by curved upper and lowerseries of tubes 32 and 33, the-upper tubes 32 providing for Feed .the passage of steam liberated in the drum 21 to the drum 22, where the moisture 'carried'over with this steam is deposited, and almost dry steam vpasses out through the i e connection or steam nozzle 34 for use. Erbe between the levels of the two lower drums,

' bafile.

the difference in level being just enough to cause circulatlon. f

The drum 2l is disposed between drums' 16 and 18 and hasits axis substantially in the vertical plane of the center of gravity of the ring circuit structure, as illustrated, so that this structure, comprising the drums and tubes and baffles, is thus suspended in proper position and without any appreciable tendency to rock or tip either forwardly or rearwardly. The drum 22 and the bank of tubes 29 connecting it to drum 16, act as` anchor or stabilizing means to hold the ring circuit structure against tilting movement, as will be clear from the drawing, this means being highly effective in this respect due to the positioning of drum 21 between drums 16 and 18, above described.

The space 27 provides accommodation for a superheater of any preferred or well known type. It will be apparent that the superheater is in the path of the gases immediately after passing through the lower bank of tubes designated at 23, where the temperature of the gases is very high. This serves to reduce'the size and first cost of the superheater to the minimum, but where the gas temperature is suiciently reduced so as to avoid danger of burning the superheater. This location of the super-heater is very favorable to the securing of the very high degrees of superheat now coming into.A 1 general practice, and 1s equlvalent to that secured by the drop header or omitted tube type of nearly horizontal straight tube boilers, which has proven so advantageous that it has been generally adopted in spite of the increased expense.

In connection with the arrangement of the tubes, drums and superheater as described, a novel arrangement of baffles or baffle walls is provided. The row of tubes 26 forms means 'for supporting a :similarlyl inclined first baiile 38, which extends from the lower or mud drum v16 upwardly along the to-p portions of the tubes 26, which latter are `well separated from the tubes 25 and so arranged to partially support the This exposes the bottom of the tube or row of tubes 26 to the comparatively hot gases between the first and second banks of tubes 23 and 24 respectively, and as the baffle 38 terminates above the bent portion of the tube 26, an escape passage is provided between the upper end thereof and the drum 21 so that the top of thetube 26 is exposed to the gases passing between'the second and third banks of tubes 24 andy 25 respectively. is here pointed out that the tube or row of tubes 26 can be placed parallel to either the -second or' third banks of tubes and rthe baffling arranged in -any other suitable manner, but the same is here shown provided with a baiiie wall 39 extending partially across the bank 24 from the upper end of the baffle 38 and with arearward baffle 40 extending to the bank 25 and suitably supported as by means of a bracket or other suitable device 41 attached to the lower tubes of the-bank 25. These baffles 39 and 4() branch out in diverging relation as shown so that after passing around the superheater 35, the hot gases pass through the next bank of tubes 24, being preferably forced to pass partly or wholly crosswise, as shown, and by means `of the baffle 39, but in certain 'sizesor proportions, not shown, passing parallel to these tubes, in which case the baflie 39 is made shorter or entirely omitted. It will thus be apparent that the gases will traversey the tubes of the bank 24 twice, first forwardly and then rearwardly across the lower and upper portions thereof respectively, after which, the gases are caused by the baffles 39 and 40 to enter and partialbank of tubes, at right angles thereto.

this point, the gases are caused to pass downwardly along the tubes 25 by means^of a' baffle 42 on the upper side thereof and extending between the drum 21 anda point in spaced relation to the lower or mud drinn 16, at which point'a baffle plate or wall in the form of a partition 43, is extended between the lower end of the baffle 42 and the adjacent portion of the tube bank 29, being A i as desired or as is common practice in the art. In some cases, `not shown, the tubes 25 may be cross baiiied to secure three cross- Wise passes around the tubes 25, though it is to be understood that the gases after passing over the baiie 40 and entering the tubes 25 at right angles thereto, will be caused to' again cross the tubes 25 forwardly toward the baie 38 and then cross the tubes 25 to exist at approximately right angles into the last bank of tubes 29 at the lower portion thereof, with the construction disclosed, thus securing approximately the same result as if an additional baille was provided across the tubes 25. It may also be pointed out that the use of the baille 39 is optional, and that the space between the bank 24 and the front wallv 11 of the setting,

passage below the baffle 43, the gases then...v

pass upwardly along and substantially parl allel to the tubes of the bank 29 adjacent the rear wall 12 of the setting. However, the

"tubes 29 may be and preferably are partially cross baffled to similarly affect the gases.

as shown, to secure better contact with these tubes, and secure a greater heat extraction when suilicient suction is available, or ma pass parallel to the tubes when less dra t is available. For' this purpose, a cross baffle 46 may be provided at the rearlportion of the tubes 29, substantially horizontally and intermediately of the lengths or upper and lower ends thereof, but preferably nearer the upper ends of the tubes 29 and the adjacent drum 22, while the rear Wall 12 may be provided with an inwardly extending horizontal ledge or shoulder 47 supporting a short baille wall 48 in conjunctionwith the adjacent outer or rear end of the baille 46, the baille 48 extending inwardly from the wall 12 to throw the fire gases towards the tubes 29 and prevent the same from passing up between the wall and the bafiie or rear tubes of the bank 29, during their upwardr passage to the smoke exit 30. In this manner, the gases are, therefore, caused to be deflectedforwardly across'the tubes 29 by the baliles 46 and 48, instead olf lan-ing along parallel to the tubes 29 the full lengths thereof, said gases after passing into the space between the banks 25 and 29 ,then

passing rearwardly across the tubes 29 above the baflie 46 and finally out the smoke exit. However, during this action, said gases will act upon the tubes 32 and 33 and the upper drums, to secure greater efficiency.

rFeed water is preferably introduced into the upper drum 22 through a feed water pipe 49, either fromA the main r a feed water prev-heater, so that the comparatively cold feed water passing down through the bank of tubes 29 willbe absorbing the heat from the gases just before their exit, and gain a higher thermal head at this point, thus absorbing a greater total amount of heat from these gases and gaining some of the advantages of an economizer. Thus, it will appear that the bank of tubes 29 serve an economizer function. As shown, the lower or mud drum 16 is also provided with a clean-out or blow-ofi;l 50 for cleaning out the mud drum and system, and said pipe may be provided with a suitable shut olf valve as indicated. 4

L- This boiler has the advantages of the v straight tube boilers in exposing more or less length of thel bottom row of tubes to absorption of radiant heat from the fuel bed of its e uivalent, this amount being varied by varying the distance .between the lower drums, thus varying the length of these low-` er tubes. In the present state of the art of furnace design and construction, the length of these tubes exposed to radiant heat would be so proportioned as to maintain the furnace temperature within such limits as would not be destructive to the furnace linings. Furthermore, the number of tubes shown in any or all of the banks may be varied to meet various conditions, but the respective areas for the passage of steam and water in each of these banks should be such as to cause no restriction to their passage and give a free circulation for the liberation of steam, and its rapid removal from the interior of the heating surface at all rates of evaporation. The tubes 26 serve as an element of the boiler, in addition to supporting the baille 38.

The drum 21 is preferably disposed back A of the drum 18 so as to leave a space 6() in which an additional superheater 61 'is disposed. The superheater 61 may be employed to great advantage as an interstage heater for turbines. If desired the superheater 61 may be employed as the primary superheater of the boiler. lts position, i. e., between the second bank 24 of tubes and front wall 11 makes it admirably adaptable to use as an interstage heater:

This superheater 61 comprises the hairpin shaped tubes 62 connected to manifolds 63 and 64 for intake and discharge of steam respectively. Suitable flanged nozzles 65 and- 66 are connected to the manifolds 63 and 64 respectively for connection between stages of a turbine or between a high pressure and a low pressure turbine, which have not been shown because they are well understood by those skilled in the art and form no part of my invention.

The operation of the device as shown and described is vas follows; water is fed into or supplied to the drums through the feed water pipe 49 into the drum 22 or otherwise, as desired, until the water level reaches the normal water level ordinarily employed, whiclr is approximately slightly below the centers of the drums 21 and 22 as indicated. Water being present in all of the drums and the banks of tubes connecting the same, the heat from the lire bed is brought into action by the gases passing or flowing upwardly from the' burner across the tubes of the bank 23 and around the other banks of tubes and baffles or baille walls in a manner indicated by the curved arrows in the drawings. The straight arrows indicate the direction of flow of the water in the tubes from the respective drums or headers. 'The gases,

products of combustion and smoke escape out through the smoke exit or flue 30 through the stack or flue. The gases, after passing the tubes of the bank 23, may pass over the superheater'35 as shown to dry the steam which has been previously generated and passed therein by connection with the drum 22, from which it may be drawn H as indicated in dotted lines in the drawings for use in adry efcient form orthis superheaterl may be omitted. The y gases are caused by the baffles 38 and 39 to pass across the tubes vof the bank 24 toward the front wall 11 and then rearwardly over the upper 1mportions of said tube above the baffle 38 and the baflies 39 and 40 acrossv the upper portions of the tubes of the bank rearwardly and then downwardly along the same and then rearwardly beneath the baiflles 42 and 43. The gases then pass rearwardly across the tubes of the bank 29 and are deflected forwardly across said tubes in an opposite direction by the baflies 46 and 48, subsequently passing rearwardly across the 4upper portions thereof and out the smoke exit 30. As the water in the tubes 23 is heated,

it flows upwardly through the same and into the water drum 18, and then upwardly the tubes 29, the same becomes pre-heated so that said bank of tubes acts as an economizer, extracting the heat from the gases immediately prior to their exit at 30. v As previously stated, the steam may be drawn off from the drum 22 by the connection 34 or .superheated in -the superheater 35, as required generally in high pressure practice. Furthermore, any water which is carried over in the tubes 32 from the drum or header 21 to the header 22 is either generated into' steam or discharges into the header or drum 22 and finally circulates in the ring circuit boiler arrangement described for the generation of steam. The How in the tubes 26, may correspond with the flow in the tubes 25 or may be upward according to the arrangement and location thereof. Moreover, they are subjected to the action of the gases beneath the baille 38 after passing the superheater 35 and also after passing forwardly over the tubes 24, `in passing rearwardly across the top portions of said tubes across the baiiles 38, 39 and 40 prior to entering the upper portions of the tubes 25. This construction and arrangement gives high vsteam generating capacity with a minimum of fuel consumption. l

If desired the steam discharge nozzle 34 may bemounted on drum 21 for the dis charge of steam therefrom. The groups of tubes 32. and 33 or either of them may also be omitted if desired, depending upon the tubes 25 and 29 and drum 16 for equaliza- .ftion.

While I have now described the form of the invention which I now consider to be the preferred embodiment, it is to be understood that various alterations in the arrangements vof the parts and form and construction thereof, may be made so long as the same do not departfrom the spirit and scope of the invention as defined in the claims appended hereto. f

I claim: 1. In combination, a boiler casing having a front wall, a boiler in said casing comprising a mud drum at the back of the casing, a4

water drum slightly above the mud drum and disposed at the forward side of the casing and sealed with the front wall, a steam and water drum disposed at a higher level than the water drum and between the water drum and the mud drum, tubes connecting said three drums in a ring circuit, a'furnace in the lower part of the casing, the tubes joining the mud drum and water drum being inclined at a small angle to the hori- Zontal to provide'circulation, the length of said tubes being proportioned to the capacity of the furnace so that the fire gases flowing from the furnace strike across said tubes and ll the entire space through which said tubes vare projected, and a baliie disposed above the lower tubes so as to provide a relatively large gas space above said tubes along their full length, and a bent tube type ofsuperheater disposed in the aforesaid gas.

space substantially parallel to the lower- E most bank of' tubes.

prising'a mud drum at the back of the casing, a water drum slightly above the mud' drum and disposed at the forward side of the casing and sealed with the front wall, a steam and water drum disposed at "a higher level than the waterpdrum and between `the water drum and the mud drum, tubes connecting said three drums in aring circuit, a furnace in the lower part of the casing, the tubes joining the mud drum and water drum being inclined at a small angle to the horizontal to provide circulation, the length of said tubes being proportioned to the capacity of the furnace so that the ire gases flowing from lthe furnacestrike across said tubes and fill the entire space through which said tubes are projected, and a baie disposed above the lower tubes so as to provide a relatively large gas space above said cross passes with respect to said latter tubes, and an interstage superheater disposed in the space above the water drum and between the latter tubes and the front wall of the casing. l

3. In combination, a boiler casing having a front'wall, a boiler in said casing compris! I ing a mud drum at the back ofthe casing,

wardly and rearwardly of the casing, a series of tubes connecting the 'mud drum and the steam and water drum, the tubes of said series being disposed in the space enclosed by the banks of tubes and being inclined oppositely to the bank of tubes connecting the water drum to the steam and water drum, and a baiile supported by the tubes of said series and extending upwardly from the mud drum', said baiile terminating short of the steam and water drum.

4. In combination, a boiler casing having a front wall, a boiler in said casing comprising a mud drum at the back of the casing, a water drum above the mud drum and adjacent the front of the casing, and a steam arid water drum above and betweenl the water drum and the mud drum, banks oi'* tubes connecting the drums in a ring circuit,- the tubes connecting the water drum to the steam and water drum being inclined upwardly and rearwardly away from the front wall of the casing, a superheater disposed between the front wall of the casing andl the bank of tubes connecting said water drum to the steam and water drum, a series of tubes connecting the mud drum and the steam and water drum and inclined upwardly and forwardly of the casing, said series of tubes being disposed in the space enclosed by the banks of tubes, and a baiile supported by thetubes of said lseries and extending upwardly from the mud drum, said baie terminating short of the steam and water drum.

5. In combination, a boiler casing'having a front wall, a boiler in said casing comprising a mud drum at the back of the casing, a water drum above the mud drum and adjacent the front of `the casing, and asteam and water drum above and between,

the water drum and the mud drum, banks of tubes connecting the drums in a ring circuit, thetubes connecting the water drum to the water and steam drum being inclined upwardly and rearwardly of the casing, a

series of tubes connecting the mud drumv and the steam. and water drum, the tubes of said series being disposed in the space enclosed by the4 banks of tubes and being inclined oppositely to the bank of tubes connecting the water drum to the steam and water drum, and a baffle supported by the tubes of said series ,and extending upwardly from the mud drum, said baie resting upon the upper surfaces of the tubes and termii nating short of the steam and water drum. 6. In combination, a boiler casing having a' front wall, a boiler in said casing compris- `ing a mud drum at the back of the casing, a

water drum above the mud drum and adjacent the front of the casing, and a steam and water drum above and between the 4water drum and the mud drum, banks of tubes connecting the drums in a ringrcircuit, the tubesl connecting the water drum to the steam and water drum being inclined upwardly and rearwardly away from the front wall of the casing, a series of tubes connecting the mud drum and the steam a steam and water drum disposed in sub;

stantially triangular arrangement, the steam and water drum being above and between the mud drum and the water drum, banks of tubes connecting the drums in a ring circuit and enclosing a substantially triangular space, a series of tubes disposed in said space and connecting the mud drum and the steam and water drum, the lower portions of the tubes of said series being inclined oppositely to and extending `toward the.` tubes of the vbank connecting the water drum to the steam and Water drum, and a baile supported by the tubes of said series and extending up wardly from the mud drum, said baiile ter- ,and water drum and inclined upwardly and v minating short of the 'steam and water drum.

8. In combination, va boiler casing having a front wall, a boiler comprising a mud drum adjacent the back of the casing, a` water drum above the mud drum and ad. jacent the front 'wall of the casing, and steam and water drum above and between the iiiud drum and the water drum, banks of tubes connecting thedrums in a ring circuit, said banks of tubes enclosing a substantially triangular space and the tubes of the bank connecting the water drum to the steam and water drum being inclined upwardly and rearwardly of the casing, a series of tubes disposed in said s ace and having ,theirV lower portions inclined upwardly and forwardly of the casing, anda main bale supstructure,

ported by said series of tubes and extending upwardly from the mud drum, said baille terminating short of the steam and water drum and being spaced an appreciable distance above the lower bank of tubes connecting the mud drum and the water drum thus providing a space of appreciable height above said lower bank of tubes facilitating flow of the products of combustion from the furnace transversely of the tubes of the lower bank.

9. In combination, a boiler casing, a boiler comprising a mud drum, a water druln, and a steam and water drum disposed in substantially triangular arrangement, the steam and water drum being above and between the mud drum and the water drum, banks' of tubes connecting the drums in a ring circuitand constituting. a ring circuit structure enclosing a substantially triangular space, said mud drum andthe water drum'beinrr disposed below ,the center of gravity of said a series of tubes disposed in said space and connecting the mud drum and the steam and water drum, the lower portions of the tubes of said series being inclined oppositely to and .extending toward the tubes of the bank connecting the water drum to the steam and water drum, and. a baille supported by the tubes of said series and extending upwardly from the mud drum, said baflie terminating short of the steam and water drum.

In witness whereof, Iyhereunto subscribe my name ,this 21st day of February, 1 925.

ASHUR U. WETHERBEE. 

